Foam inhibited oil



FoAM'NbEX (If) 'Junb 1945- A. H. BATCHELDER ETAL 92 FOAM INHIBITED OIL Filed Dec.18,' 1943 2 Sheets-Sheet 1 0 non 0.2 0.1 0.4 0.51 CONCENTRATION OF Z'NITRO-I-BUTANOL INVENTORSI v PERCENT'BY WEIGHT 1 AUGUSTUS- H. BATcHEL-DER .TBAsED 0N FINISHED On. V 5 FITZHU Hi 'FIG.3'

I @ATTORNEY J 1946- A. H.BATCHELDER ETAL 2,402,487 I 1 6m INHIBITED on I med- Dec. 1a, 1943 2 Shets-Sheet z Z- NITRO :1 BUTANOL c f u z-AMlNjzl BUTANOL Q Z-AMINO-Z-METHYL- -/1-PROPANOL FIGA . INVENTORS AUGUSTUS H. BATCHELDER TORNEY FITZHUGH S. RoLL1Ns,JR.

Patented June 18, 1946 2,402,487 FOAM mmsrmn on.

Augustus H. Batchelder and Fitaliugh S. Rollins,

Jn, Berkeley, Calif., assignors, by meme assignmerits, to California Research Corporation, San Francisco, Calif., a corporation of Delaware Application December 18,1943, Serial No. 514,782

1 This invention relates to the inhibition of I foaming in hydrocarbon lubricating oils.

On mixing oil with air, a certain amount of 9 Claims. or. 252-51 foam may be created. The amount of foam and its persistence will depend upon a. number 01 factors, such as the nature of the base oil, the nature and amount of compounding agents present in the'oil, the temperatures and pressures to which the oil'is subjected, and the nature of the lubricating .system that supplies lubricant to the relatively moving surfaces.

Under most conditions of use uncompounded base oils and even many compounded oils will not produce troublesome foaming; either the degree of foaming is small or the foam is unstable and breaks down readily, or both conditionsobtain.

There are, however, certain combinationslof circumstances that have-brought to the fore the problem of foaming and it is an object much sought in the art to inhibit foaming of mineral oil lubricants. Among these combinations of circumstances is the use of mineral oils compounded with'metal salts of organic and/or organo-substituted inorganic acids to lubricate aircraft engines. These compounding agents, which are highly desirable as stabilizing and scavenging components of the better grades of aircraft lubricants, frequently increase the tendency of lubricants to foam. Moreover, aircraft engines are nowadays more frequently called upon to operate at high altitudes, where the atmospheric pressure is low; for example, at elevations as high as, 45,000 feet above sea level, where the normalpressure corresponds to a. 25 inch (mercury) vac-' uum inch absolute pressare) at sea level. Such low pressures aggravate foaming greatly, especially in the Presence of water, which vaporizes quickly at the reduced pressure and produces excessive foam. An added factor causing excessive foaming of aircraft lubricants is the suits from the loss of oil from the crankcase and oil sump caused by foaming. Not only does this represent a costly loss of oil but it creates a fire hazard. I

It is an object achieved by the present invention to inhibit the foaming of oils.

It is a particular object achieved by the present invention to inhibit the foaming of hydrocarbon lubricating oils which are compounded with metal salts of organic and/or organosubstituted inorganic acids.

., It is a further particular object achieved by'the present invention to inhibit, the foaming of aircraft lubricants and other lubricants brought on by a combination of circumstances such as the presence in the oil of foam-inducing compounding agents, use of the oil at low pressures, and circulation of oil under conditions that produce violent intermixture of air or othergases with the oil.

These and other objects will be apparent from the description of the invention and the appended claims.

We have found that the nitro-substituted aliphatic alcohols and primary amino substituted aliphatic alcohols having at least one hydroxyl group per four carbon atoms (an OH/C molecular ratio at least 1&4) are exceedingly effective .vention are as follows:

type of lubrication system employed. In this system, 011 from the moving parts of the motor is collected in the crankcase and pumped from there to an external tank or sump by a scavenging pump. 011 from this sumpis pumped back to the motor in the usual manner by an oil pump, The foaming difficulty arises from the fact that the scavenging pump operates at excess capacity;

it pumps faster than required to pump all of the available 011 in the crankcase. It therefore pumps a lar e amountof. crankcase g'asesalong with the.

oil, and this at a rapid rate, and theresult is, en-

trainment of the gas in the of foam.

A disadvantage of excessive foaming of lubricating oils is that the oil pumped to thebearings is aerated and, as a result, insufllci ent lubricant may-be supplied to the bearings 'undersome conoil and the formation ditions of operation. Another disadvantage re- 1-nitro-2-butanol l-amino-z-butanol l-nitro-ii-butanol 1 amino-fi-butanol 1-nitro-4-butanol 1-amino-4-butanol z-nitro-l-butanol 2-am1no-1-'butanol 2-nltro-3-butanol -2-amino-3-butanol z-nitro-i-butanol 2.-amino-4-butanol 1- n1tro-2-propanol 1-amino-2-propanol 2'-n1tro-1-propanol 2-amino-1-propanol 2-nitro-2-ethyl-1,3- 2-amino-2-ethyl-L3- propanediol .propanediol 2-nitro-2-methyl-1- 2-amino-2-methyl-1- propanol propanol Ethanolamine The nitro alcohols, suchas z-nitro-l-butanol, are preferred to the amino alcohols; besides be-' ing potent foam inhibitors, they are also more effective in reducing the em'ulsiflcation of water with oil andthey are substantially non-corrosive to copper-lead and cadmium-silver alloy bearinss.

j Nitro and amino alcohols containing as many as eight carbon atoms foam inhibitors.

or more may be used as b test and the Cadillac test.

' pressure.

under the conditions of certain foaming tests,

these tests being designated as the Wisconsin These tests are carried out as follows:

Wisconsin test-The equipment used in this test is illustrated diagrammaticallyin Figures 1 and 2 of the drawings.

Referring to'Figure 1, engine I is a 1 H. P. Wiscon single cylinder air-cooled gasoline engine comprising cylinder 2 and crankcase 3. Crankcase 3 is provided with outlet line 4 (which is provided with valve 5 and gear pump 6) and with inlet line 1 (which is provided with valve 8 and gear pump 9). Line 4 communicates with flask l through tube H which passes through and is sealed to the wall of flask [0 near the bottom. Flask l0, which is a round bottom flash of liter capacity, is provided with an outlet tube ii at the bottom, which communicates with.

the aforesaid line 1. Flask I0 is also provided with s opper l4 and a temperature measuring degrammatic cross-section, a portion'of engine l on the outlet side of the crankcasaand it shows outlet tube 2|, which has a slanted opening at the top such that part of the opening projects above oil level 22 and part below said oil level.

' In this manner, by applying suction to outlet tube 2| through line 6, both oil and crankcase gases are pumped'from crankcase 3. Oil level 22 may be controlled by pumps 0 and s and valves 5 and 0.

In operation, engine i is run at a cylinder temperature of 450 F50 F. Oil is pumped from 'crackcase 3, by means of gear-pump ,8 and by proper adjustment of valve 5 at a rate such that 50-60% of the total volume of pumped fluid consists of gases and the remaining 50-40% conof oil. This mixture of gases and oil is passed through line 5 and inlet tube i! into flask 10. By appropriate adjustment of valve 8 and gear. pump 0, the oil level in'fiask I0 is maintained at the halfway mark on the flask, as shown by scale E2. The system is also operated so that the oil temperature in flask i0 is 135-140 F. and so that the jet of oil and gas mixture entering flask l0 through inlet tube H produces a fountain above the level of the oil in the flask which is l to 1 inches high.' A vacuum is pulled on outlet tube l0 so as to maintain a suitable reduced pressure in flask l0.

The foam index of an oil is calculated as follows: An absolute pressure of 5 inches of mercury is maintained in flask W. The height of foam above the oil level is measured .on scale H at this Then the pressure is decreased until the line of distinction between the oil and the foam just becomes indistinguishable. The roam. index, I1, is given by the equation h I x 100 where his the foam height in inches at 5" abso-' lute pressure, P is normal atmospheric pressure in inches of mercury (29.9") and p is the recorded absolute pressure in inches of mercury at which the line of demarcation between oil and foam Just becomes indistinguishable. Ir, there- 4 fore, reflects both the foaminess of an oil at a given low pressure (5" of mercury) and the extent to which pressure can be reduced before foaming becomes complete. I: provides a reliable index of the foaming characteristics of an oil, especially in an aircraft lubricating system where sump and back again to the crankcase and where the engine is operated at high altitudes.

Cadillac test-In this test a 1938 Cadillac passenger car engine equipped with an external oil sump is used. The oil circulatin system is modified by substituting for the regular engine suction line a special intake line leading from the sump to the crankcase. A scavenging line provided with a gear pump is connected with the bottom of the crankcase and with the sump. In operation oil is pumped from the crankcase through the scavenging line by the gear pump, which is operated at about 200% of the capacity needed to keep the crankcase empty; by this means a large amount of crankcase gases is pumped with the oil to the sump and is churned into the oil. Additional turbulence is provided in the sump,

by directing the oil stream toward both side walls of the sump. Foaming, as measured by foam Table I Cadillac test. loam height in i inches at- Oil I cum inhibitor sin test OilA Nil 35 8+ 8+ Do... 0.05%-2-nitro-l-butanol 10.9 Do... 0.10% 2-nitro-1-butanoL 2.9 Do... 0.15% 2-nitro-1-butauol- 3.3 0.3 0.0 Do... 0.25% 2nitro-l-butanol 2.2 Do... 0.20% 2-nitro-2-ethyl-L3-pro- 6.0

. pane '01. Do. 0.20% Z-nitroZ-methYI-bpro- 6.0

panol. Do... 0.25% l-nitro-Z-propanol 8.5 Do 0.05% 2-amino2methyl-l-pro- 14.0

panol. Do. 0.25% Z-amino-Z-methyl-l-pro- 2.7

panol. Do. 0.20% 2-amino-2-ethy1-l,3-pro- 10.0

pam 01. Do... 0.05% 2-amino-l-butanol 10.5 Do... 0.25%2-amino-l-butanol 3.3 OilB Nil 21.5 Do... 0.15% Z-nitro-l-butanol 8.3 0ilC Nil 8.3 8+ 8+ Do... 0.25% 2-nitro-l-butano] 3.3 2.3 1.0

The oils referred to in the above table as oils containing about 2 per cent of a mixture of the same phenate, phosphate and sulfide as in oil A. 011 C was an SAE 30 Pennsylvania type 011 having a viscosity index of and containing about 0.75% of the barium salt of an alkyl phenol disulfide and about 0.15% of octadecyl alcohol. All pelrcentages are by weight based onthe finished o i 1 foam index (I1).

the finished oil.

foam-inhibitors ofthe pm; invention mayvbaincorporatedintoil in variouswfly 1 .eexemplifledrbythefiatain .IableH. and

I from" the. results "of an emulsiflcation addition *of othericemponnding material, air it I may be added to theicompounded oil. iinp 'epa ing oiis compounded with edetergents, oxidation -inhibitors,:extreme pressure agents and the like,

it is a common practice to producea concentrated solution or .dispersion of these compounding agents in amineral oil, which is subsequently blended with base oil to produce the finished oil. We have found that the foam inhibitors of the present invention are advantageously incorporated in compounded lubricating oils by first including the foam inhibitor in a concentrate of the compounding agents and adding the thus modi-, fied concentrate to the base oil. Another way in which the foam inhibitors ofthe present invention may be added to oils i to add the foam inhibitor directly to the oil in an engine; for example, by adding it to the engine sump.

' The foam inhibitors of the present invention,

, especially the nitro-alcohols, are preferably dried "test which equal volumeso'f the oil under test and water are "vigorously together to produce an emulsion and the'resulting emulsion :.is'then.acentrifuge11 to separate the mixture into "an oil phase, *a water; phase and an emulsion ,phase ,'which-is-called *c IYhecufiis a-cz'eamy emulsion which lies betweenthe bottom "water phase and the :top oil phase. The fiata in abIe H refer to tests .of whichwere-carried out in exactly the same manner except for variation of the base oil and additive components of the oil.

centrate or in the base oil or finished oil. This may be accomplished, in the case of a liquid foam inhibitor, by keeping it in contact with anhydrous sodium sulfate or other suitable dehydrating agent overnight and then filtering it. A solid foam iniurtherillustrate the foam inhibiting effects of the inhibitors of the present invention.

Oils A and C were the same as oils A and C, respectively, of Table I.

It will be noted that in each case' the volume -.of oil at the conclusion of the test constituted 50% ornearly 50% of the total volume; that is, in any case very little oil became emulsified in water. However, attention is directe to the fact that in actual practice, although verylittle oilmay be emulsified in water, a great deal of oil-in-water emulsion may be formed; in fact, a

great deal of oil-in-w'ater emulsion is formed in In both Figure 3 and Figure 4, abscissae represent concentrations of foam inhibitor by weight based on finished oil and ordinates represent All data were obtained in the Wisconsin test. The oil tested was the same as oil A'of Table I. 1

, out preliminary drying was added to the oil compounded with phenate, thiophosphate and sulfide in the proportions indicated. Curve B represents certain types of service. This emulsion would remain mechanically dispersed throughout the oil where it is undesirable because it impairs lubrication and may cause'early engine failure.

The foam inhibitors of the present invention may be used in oils in the amount of 0.001 per ,centor lower to 1 per cent or'h'ig her' by weight based on the finished oil, but percentages of oil prepared as follows: A concentrated solution.

in mineral oil of the phenate, thiophosphate, sulfide and 2-nitro-l-butanol was prepared and this concentrate was blended with more oil to produce Curve 0 represents an oil similarly prepared except that the 2-nitro-1-butanol was dried before it was added to the concentrate.

It is evident from curves A, B and C of Figure 3 that it is advantageous to add the foam inhibitor to a concentrate and then add the concentrate to the oil, and it is also evident that it is advantageous to dry the foam inhibitor before adding it to the oil.

Figure 4 shows graphically the foam inhibiting effects of various inhibitors of the invention and, as will be apparentirom the curves, the optimum concentration of inhibitor is about 0.2 to 0.4%, varying somewhat with the inhibitor.

, Among the foam inhibitors of the present invention, the nitro alcohols are notable for their demulsifying properties. This is especially important in certain types of service, such submarine and other kinds of marine service, where water leakage into the oil sump occurs. The demulsifying properties of the nitro alcohols are about 0.01 to 0.5 are referred. Wherethe foam inhibitors are used in oils cqmp unded with chemical additives that produce foaming, the foam inhibitors may be used in the amountof 0.1 to 100 per cent by weight based on the said chemical additives, preferably about 1 to per cent based on the said chemical additives.

Concentrated dispersions in mineral oil of the foam inhibitors may be prepared for later blending with base oil to produce finished oil. As stated, the foam inhibitors are advantageously added to concentrates of other compounding agents. Besides the observed effect of increased I foam inhibiting capacity so obtained, this procedure has the advantage that a small weight of concentrate can be prepared at one time and place andblended with base oil at its source or place of use and at a later time to produce a finished oil having the required properties, including reduced foaming tendency. Such concentrates may certain conditions, enhance foaming and with phosphates and calcium, barium and zinc cetylphenyl thiophosphates; metal organo sulfonates such as calcium, barium and zinc petroleum sulfonates and calcium, barium and zinc cetylphenyl sulfonates; calcium, barium and zinc naphthenates; and calcium, barium and zinc salts of the dithiocarbamates produced by reacting reduced petroleum nitrogen bases (alkyl piperidines) with CS2 in the presence of KOH and producing the calcium, barium and zinc dithiocarbamates by double decomposition of the potassium dithiocarbamate'with aqueous CaClz,

itors specifically mentioned hereinabove may be used in lubricating oil in combination with each of the above mentioned metal salts and-with combinations of the said metal salts. Examples of such combinations are as follows:

Metal salt compounding agents Foam inhibitors +2-nitro-l-butanol. +l-nitro-2-propanol. +Ethanolamine.

+2-nitro-l-butanol. +l-nitro-2-propanol. +Ethanolamm' e. +2-amino1-butanol.

. i%-liiiigo-:butanol.l

opropano. +Ethanol e. +2-amino-l-butanol.

+2-nitro-1-butanol. +1-nitro-2- ropanol. +2-nitro-lutanol.

+l-nitro-2-propanol. +Ethanolamine. +2 amino-l-butanol.

+2-nitro-l-butanol. +2-amino-l-butanol. +2-nitro-l-butanol. +2-amlno-1-butanol. +2-nitro-l-butanol. +2-amino-1-butanol. +2-nitro-l-butanol.

+2-amino-l-butanol.

(1) Calcium cetyl phenate l .l

Salt No. (l) +salt No. (2)

- 0 Sult'No. (l) +salt N0. (3)

o Salt 113i 0. (l) +salt No. (4)

o Salt No. (5) +zinc di-(methylcyclohexyl) thigphosphate.

I By calcium cetyl phenate is meant the calcium salt of the alkylated phenol produced by condensing phenol with a butene polymer in the presence of concentrated sulfuric acid, the butene polymer averaging 16 carbon atoms per molecule.

For the purpose of defining the foaming characteristics of an oil; of indicating whether the oil is one which causes troublesome foaming under certain conditions of use, either a test such as the above described Wisconsin and Cadillac tests. or a test in an aircraft engine provided with an external sump and flying at a high alti- BaClz or ZnClz. Thus each of the foam inhibtude, may be used. An "excessively foaming oil may be defined as one which gives a foam index, 11, using a 5" absolute pressure to obtain the numerator of the ratio -ip of 15 or above. Or an excessively foaming" oil may be defined as an oil which, when used as the crankcase lubricant of an aircraft engine provided with an external sump through which the crankcase lubricant is passed and flying at an elevation greater than 30,000 feet above sea level, will roam sufiiciently to cause substantial loss of oil through the breather'caps.

We claim:

1. A method of producing foam inhibited lubricants, comprising incorporating a short chain nitro aliphatic alcohol containing at least one hydroxyl group for each four carbon atoms into a mineraloilof lubricating viscosity to'produce a concentrated dispersion of the said alcohol in mineral oil, and blending the said concentrated dispersion in mineral lubricating oil toproduce a lubricating 011 containing a smaliamount, suiflcient to inhibit foaming of the oil, of said alcohol.

2. The method of claim 1, wherein said nitro aliphatic alcohol is 2-nitro-1-butanol.

3. A lubricating composition comprising a hydrocarbon lubricating oil substantially free from water, at least one salt which improves the lubricating properties of the oil but which causes an increased tendency of the oil to foam, said salt being selected from the group consisting of metal salts of organic acids of the class of sulfonic and phenolic acids and metal salts of organo-substituted inorganic acids of the class of phosphoric and thiophosphoric acids, and a small amount. suflicient substantially to inhibit foaming of the oil, of a short chain alcohol selected from the group consisting of nitro aliphatic alcohols and primary amino aliphatic alcohols, said alcohol containing at least one hydroxyl group for-each four carbon atoms.

4. The lubricant of claim 3 wherein said salt is an oil-soluble polyvalent metal salt of an alkyl- I ated phenol.

5. The lubricant of claim 3 wherein said salt is an oil-soluble polyvalent metal salt of organesubstituted phosphoric acid..

9. A lubricating composition comprising a concentrated dispersion in mineral oil substantially free from water of at least one salt selected from the group consisting of metal salts of organic acids of the class of sulfonic and phenolic acids and metal salts of organo-substituted inor anic acids of the class of phosphoric and thiophosphoric acids, and a short chain alcohol selected from the group consisting of nitro aliphatic alco hols and primary amino aliphatic alcohols, said alcohol containing at least one hydroxyl group for each four carbon atoms.

' AUGUSTUS H. BA'I'CHELDER. FITZH'UGH S. ROLLING, JR. 

